Mr Young, who once owned a portfolio of expensive properties, claims he is now penniless after a large Moscow real estate deal collapsed.

They couple, who both live in London and have two daughters, met face to face in court again today as it was argued that he had ignored court orders.

Two years ago he was ordered to pay £27,500 per month in maintenance for rent and school fees and she claims he has flouted the judge's rulings.

Mr Young was compared to a character in the film Brewster's Millions when he said he could not pay his estranged wife a share of his fortune because he had lost it all.

In the 1985 film, Richard Pryor plays Montgomery Brewster, who has to spend $30 million dollars in 30 days to inherit $300 million.

The couple once shared an extravagant champagne lifestyle and enjoyed lavish holidays, choosing to travel on their private jet.

They had owned a fleet of luxury motors and yacht that was berthed in the millionaires' playground of Monaco.

Now Mrs Young, 48, believes he has "secreted enormous assets".

Edward Fitzgerald QC, representing her, argued that Mr Young had not complied with orders forcing him to reveal details of his finances and should therefore be jailed for contempt of court.

But the tycoon, who is representing himself, hit back claiming that his wife had hired private detectives to track his every move - and said the constant surveillance was making him ill.

He claimed up to eight investigators trailed him 24 hours a day.

Mr Young said: "There's been a long history (of covert surveillance) since 2009 until today. I believe covert surveillance continues on me and it is highly illegal. This is perpetuating my health problems."

At a previous High Court hearing in November, Mr Young was ordered to make a full financial disclosure or serve the six-month sentence he was originally handed back in 2009, which was suspended.

Mr Young argued that the reason he failed to produce documents disclosing his assets was because he feared that people calling him may have been private detectives hired by his estranged wife.

He said: "When you have up to eight individuals on three shifts it is very difficult to know who is a process server and who is a detective hired by my wife."

He denied trying to “be difficult” but admitted that on at least one occasion he did not believe someone was a process server as he was paranoid about private detectives.

But Mr Fitzgerald said he owed a debt of £1million in unpaid maintenance, adding: "He has never paid a penny. He's been in breach of that order for three-and-a-half years. He has persistently failed the orders of the court."

He told Mr Justice Moor that Mrs Young was making an "application to commit" him to prison for contempt.

Mr Young had been claiming to live off gifts from friends and associates - totalling £155,000 in rent and £151,000 in "other items", Mr Fitzgerald said.

"There is no documentation in relation to any of that. This is an incredible claim, that all this was made in cash in relation to which there was no documentation at all."

Mr Fitzgerald added: "He was worth £400 million in 2006. He has given absolutely no explanation about where that £400 million went at all. He claims this was all lost on 'Project Moscow'."

He continued: "He has repeatedly given the court the run-around... Whilst he pleads poverty, and says he has got nothing, there is evidence of him living a lifestyle consistent with considerable wealth."

The pair's claims are due to be fully argued at a trial late this year.